1. Technical Field
The present invention relates to techniques of a gas cell, a gas cell manufacturing apparatus and a gas cell manufacturing method.
2. Related Art
A magnetic sensor using optical pumping is used for a magnetic resonance imaging (MRI) apparatus or the like. The magnetic sensor has a cell which encapsulates alkali metal atoms or the like in a gaseous state. If pump light having a circularly polarized component is irradiated onto the cell, the encapsulated atoms are excited. Further, if probe light having a linearly polarized light component is irradiated onto the cell such that the probe light intersects with the pump light, the excited atoms rotate a polarization plane of the linearly polarized light contained in the probe light in accordance with a magnetic field applied from the outside. The magnetic sensor detects a rotation angle of the polarization plane of the probe light transmitted through the cell so as to measure the magnetic field.
Since the cell is transmissive to light, at least a part of the cell needs to be formed by a transparent member. Further, the cell is required to be sealed for accommodating the excited atoms. As a technique of making an inner portion of a container formed by a transparent member into a sealed state, for example, the following method of manufacturing an image display apparatus has been disclosed in JP-A-10-64414. The method of manufacturing an image display apparatus as disclosed in JP-A-10-64414 is a method including softening a part of a glass-made exhaust pipe attached to an envelope with an electric heating unit (first process), extending the exhaust pipe in a shaft direction of the exhaust pipe so as to make an outer diameter thereof smaller (second process), heating the portion of which outer diameter has been made smaller to a temperature of equal to or higher than that in the first process again so as to melt and seal the portion (third process), cutting the molten portion (fourth process), and gradually cooling the portion with the electric heating unit (fifth process).